The video shows the unnamed mother driving the black minivan into the water at Daytona Beach as bystanders rush to save the kids inside.
"My friend pointed out that there was a car getting really close to the beach, and actually started driving on the water," eyewitness Taylor Quintin told CBS News. "I saw a kid in the back, like waving his arms around, like screaming, 'Help us! Help us!' and the car kept going deeper."
One witness who ran to the van said the mom dove out the window into the water while they were trying to save her young kids.
"She was pretty deep, and the water was moving the van, and the kids were screaming," Tim Tesseneer told CBS News. "He got the two kids out while she dove out the window, the driver's window ... just belly-flopped into the water."
Tesseneer added that the children told them there was a baby in the van.
"The kids are screaming, 'There's a baby! There's a baby!' I get back to the van, and by this time a couple of lifeguards have made it down there to us, and come to find out there's a baby still strapped in the seat, but we got her."
Authorities are questioning the mother as to why she decided to drive a minivan full of kids into the ocean. Her children are currently in state custody.
Comment: An update from USA Today:
"A pregnant South Carolina woman who drove a minivan carrying her three young children into the ocean surf off Florida had talked about demons before leaving the house, according to her sister who worriedly called police, officials said during a news conference Wednesday."
Police: Mom who drove into ocean spoke of demons